### Ramanujan and Expander Graphs

- Series
- Stelson Lecture Series
- Time
- Thursday, October 24, 2024 - 16:30 for 1 hour (actually 50 minutes)
- Location
- Bill Moore Student Success Center, Press Rooms A & B
- Speaker
- Peter Sarnak – Princeton University – sarnak@math.princeton.edu

Expander graphs are highly connected sparse graphs. They have wide theoretical and practical applications in Computer Science and Engineering. Ramanujan Graphs are optimal expanders and as the name suggests they are constructed number theoretically. We review their construction as well more recent constructions that use statistical physics. We highlight some recent applications in the reverse direction where combinatorial ideas are combined with arithmetical ones to establish expansion of graphs arising in diophantine analysis.